Multiple spindle engraving and the like machine tools



Ian. 26, 1954 A. D. GUNDERSON 2,666,989

MULTIPLE SPINDLE ENGRAVING AND THE LIKE MACHINE TOOLS Filed Oct. 3, 1949ll Sheets-Sheet 1 Emu l ilmmmfili H91 I I" I N VEN TOR.

Jan. 26, 1954 A. D. GUNDERSON 2,666,989

MULTIPLE SPINDLE ENGRAVING AND THE LIKE MACHINE TOOLS Filed 001:. 3,1949 ll Sheets-Sheet 2 quszu- MA dams ( ig 32 INvENfOR.

Jan. 26, 1954 A. D. GUNDERSON MULTIPLE SPINDLE ENGRAVING AND THE LIKEMACHINE TOOLS ll Sheets-Sheet 3 Filed Oct. 5, 1949 Jan. 26, 1954 A. D.GUNDERSON MULTIPLE SPINDLE ENGRAVING AND THE. LIKE MACHINE TOOLS llSheets-Sheet 4 Filed Oct. 5, 1949 Jan. 26, 1954 A. D. GUNDERSON MULTIPLESPINDLE ENGRAVING AND THE LIKE MACHINE TOOLS Filed Oct. 5, 1949 llSheeis-Sheet 5 INVENTOR.

Jan. 26, 1954 A. 0. GUNDERSON 2,666,989

MULTIPLE SPINDLE ENGRAVING AND THE LIKE MACHINE TOOLS Filed Oct. 3, 1949ll Sheets-Sheet 6 I a so Jan. 26, 1954 A. D. GUNDERSON MULTIPLE SPINDLEENGRAVING AND THE LIKE MACHINE TOOLS Filed Oct. 5, 1949 ll Sheets-Sheet7 I N VEN TOR.

Jan. 26, 1954 A. D. GUNDERSON 2,666,

MULTIPLE SPINDLE ENGRAVING AND THE LIKE MACHINE TOOLS Filed Oct. 3, 1949ll Sheets-Sheet 8 0h aw L L wm 8.5L 8 m T a WW/WMVZ 4? P W w-$k m m Jan.26, 1954 A. D. GUNDERSON MULTIPLE SPINDLE ENGRAVING AND THE LIKE MACHINETOOLS ll Sheets-Sheet 9 Filed Oct. 5, 1949 Jan. 26, 1954 A. D. GUNDERSON2,666,989

MULTIPLE SPINDLE ENGRAVING AND THE. LIKE MACHINE TOOLS ll Sheets-Sheet10 Filed Oct. 3, 1949 Jan. 26, 1954 MULTIPLE SPINDLE ENGRAVING AND THELIKE MACHINE TOOLS Filed Oct. 3, 1949 A. D. GUNDERSON 11 Sheeis-Sheet 11INVENTOR.

Patented Jan. 26, 1954 MULTIPLE 'SPIN'DLE ENGRAVING AND THE LIKE MACHINETOOLS Allen D. Gunderson,

George Gorton Machine 00., corporation of Wisconsin Racine, Wis.,assignor to Racine, Wis., a

Application October 3, 1949, Serial No. 119,281

27 Claims.

This invention relates to certain improvements in multiple spindleengraving and the like machine tools; and the nature and objects of theinvention will 'be readily recognized and understood by those skilledinthe arts involved from the following explanation and detaileddescription of the accompanying drawings illustrating what I'nowbelieveto-beapreferred embodiment or mechanical expression of theinvention and the several featuresthereo'f, from among various otherembodiments, designs, arrangements, adaptations, forms, combinations andconstructions, of which the invention is capable within the broad spiritandscope thereof'as defined by the appended-claims.

By my invention I'have provided a tracer controlled machine toolorganization particularly adapted, but not limited," to engravingoperations, which is characterizedby-the'use of multiple cutter spindleswith a work table mounted for universal lateral movements relative tothe cutter spindles, and a movement "transmitting mechanism of thetraceractuated, pantograph type coupled directly to theworktable foractuating the table to move simultaneously multiple work pieces mountedthereon relative to the multiple spindles, respectively, in sealedreproduction of the movements of-thetracer-in scanning a-master to bereproduced'on the work-pieces.

A general obj'ectof-th'e invention is to provide a design andarrangement of such a machine organization, and a-construction andcombination of'thecomponents thereof, to present an extremely'stable andrigid machine which is highly sensitiveand responsive'in operation andcapable of reproducing with precision and accuracy on a work :piece 'orsimultaneously on multiple work pieces, a scaled reproduction in twodimensions of the' master design.

And a further general object-is to'provide such a machine with controlswhich substantially eliminate the possibility "of operator errors, sothat reproducing'orengraving operations may be carried out onmultipleworkpieces with a minimum of work spoilage and 'atrelativelyhigh rates of production without requiring highly skilled operators.

Such a-machine organization, incarrying out the foregoing-generalobjects,.includes the following primary features:

A plurality (itself-contained motorized spin- .le units together with'a' mounting therefor, by which such units maybe individually andindependently "removed from "and replaced in mounted p'os'itions;-andbywhich; when mounted,

the units are capable of individual and inde-,- pendent adjustments'indirections axially and/or radially relative to each other;

Mechanism for feeding the multiple cutter spindle units simultaneouslyin precise synchronization to and from operative working positionsrelative to multiple work pieces, respectively, mounted on a universallylaterally movable Work table.

Electra-pneumatic mechanism and operating controls therefor, foractuating the cutter spindle unit feeding mechanism.

The mounting directly on an adjustable sup.- porting knee structure of atable unit of the universally laterally movable work table type formovement as a unit with the knee-structure; and the design andconstruction of such a work table unit which provides an arrangement ofslide rods mounted in linear, antifriction bearing assemblies to providea minimum friction, highly sensitive mounting for universaLlateralmovements of the work piece supporting table.component of the tableunit.

The combination with such a sensitive" type work table, of a pantographmechanism directly coupled therewith by which the work table isuniversally laterally movable in sealed reproduction of the movementsimparted to the pantograph mechanism by the tracer in scanning a master;

The provision for the adjustment bodily of the work table unit with thesupporting knee structure in either direction transversely of the general plane of the pantograph mechanism, without changing the position ofthe pantograph mechanism or disconnecting it from the uni,- versallylaterally movable-work supporting table component of the unit;

Mechanism for mounting onthe universally laterally movable tablecomponent of the work table unit, multiple work pieces inoperativerelation with the multiple cutter spindles, respectively, andfor indexing simultaneously in-precise synchronism, such multiple workpiecesto present different portions thereof in operative workingposition relative to the spindle units.

Electro-pneumatic means for operating .the work piece indexing mechanism,to effectsimultaneous indexingof multiple work pieces.

The system of interlocks for the work indexing actuating means andcutter spindle unit feedactuating means by which work indexingisprevented when the cutter spindle units are fed to and. are inpositions inoperative working relation with the work pieces on the worktable, andby which work indexingtmay :beefiected o rlmwhen the cutterspindle units are in positions removed from operative working relationwith the work pieces.

The provision of an indexable master unit for mounting a plurality ofdifferent patterns with such master unit mounmd for selective indexingto position a desired pattern for scanning by a tracer style mounted formovements between position in scanning engagement with a pattern andposition out of scanning engagement with the pattern.

The system of interlocks by which the master unit is locked againstindexing when the cutter spindle units are fed to and are in positionsin operative working relation with work pieces on the work table, and bywhich the master unit may be indexed only when are in positions removedfrom operative relation with the work pieces, so that, indexing of themaster unit and indexing of the work pieces may be effectedsimultaneously and only when the cutter spindle units are out of workoperating ositions relative to the work pieces;

The system of interlocks by which the cutter spindle unit feed actuatingmeans is controlled by the operation of the tracer to and from patternengaging position, to cause leed of the spindle units to workingposition with the tracer in pattern engaging position and to cause feedof the spindle units to non-working position when the tracer moves topattern disengaging position; and by which the spindle unit feedactuating means is rendered inactive to lock the spindle units againstfeed when the tracer is in disengaged position.

With the foregoing and various other objects, features and results inview, which others will be readily apparent from the followingexplanation and detailed description of the illustrated example of theinvention, my invention consists in certain novel features in design andconstruction and in combinations and sub-combinations of parts andelements, all as will be more particularly referred to and specifiedhereinafter.

Referring to the accompanying drawings in which similar referencecharacters refer to corresponding parts throughout the several figuresthereof:

Fig. l is a perspective view of a tracer controlled, multiple spindlengraving machine embodying the invention, multiple work pieces beingshown on the table supported work indexing mechanism and the multiplecutter spindles being shown in their lowered, operative positionsrelative to the work pieces.

Fig. 2 is a view in front elevation of the machine of Fig. l, a portiononly of the master wheel being shown.

Fig. 3 is a view in side elevation hand side of the machine of Fig. 1.

Fig. 4 is a view in side elevation taken of the left hand side of themachine of Fig. 1.

Fig. 5 is a view in horizontal section taken as on the line 55 of Fig.2, and showing in top plan the work table, work indexing mechanism,tracer controlled pantograph and master wheel.

Fig. 6 is a detail view in vertical section showing the pivotal couplingof the pantograph actuated linkage to the work table, and taken as onthe line 6-6 of Fig. 5.

Fig. "I is a vertical section through the pantograph mechanism and aportion of hte pivotal coupling for connecting the pantograph with thework table, taken as on the line 'l---'! of Fig. 5.

Fig, 8 is a vertical section through a pivot of of the right 4 thepantograph, taken as on the line Fig. 5.

Fig. 9 is a vertical sectional view taken as on the line 9-9 of Fig. 5.

Fig. 10 is a vertical sectional view taken as on the line Ill-40 of Fig.5.

Fig. 11 is a top plan view of the sensitive work table of the machine ofFig. 1, and showing in dotted lines the mounting and arrangement of slidrods and linear ball bearings for the table.

Fig. 12 is a vertical longitudinal section taken as on the line l2|2 ofFig. 11, showing particularly the mounting of the table directly on thesupporting knee of the machine; the work indexing mechanism mounted onthe table being shown p in front elevation.

Fig. 13 is a perspective view, partly in section, of one of the linearball bearings of the mounting arrangement for the sensitive table.

Fig. 13a is a detail vertical section through a spindle unit mountinghead showing the feed anti-backlash spring and plunger.

Fig. 14 is a view in vertical, transverse section through the work tableand its antifriction slide mounting, taken as on the line I l-l4 of Fig.11, and also showing in vertical, transverse section one of the workmounting units of the work indexing mechanism.

Fig. 15 is a vertical transverse section taken as on the line l5-l5 ofFig. 11.

Fig. 16 is a view in side elevation of the left hand end of the cutterspindle head mounting structure, and showing, partly in side elevationand partly in vertical section, the'electro-pneumatic spindle feedactuating mechanism.

Fig. 17 is a detail view in horizontal section through one of the cutterspindle unit mounting heads, a gear train of the spindle unit feed beingalso shown.

Fig. 18 is a view in vertical section through one of the cutter spindleunit mounting heads showing a spindle unit mounted therein in operativeengagement with the spindle unit feed mechanism.

Fig. 19 is a vertical sectional view through the master wheel and itsmounting, the indexing plunger and plunger lock, and the tracer arm andtracer of the pantograph mechanism.

Fig. 20 is a purely schematic diagram of the electrical circuits andcontrolling interlocks therefor, and of the electro-pneumatic spindlefeed and work indexing mechanism operating means and the air line systemtherefor.

An example embodiment of the invention and of the various featuresthereof, is illustrated and disclosed herein in the form of a tracercontrolled, multiple cutter spindle engraving machine, designed forengraving simultaneously on multiple work pieces a scaled reproductionof a selected pattern from a series of patterns mounted on an indexablemaster unit. The invention is not, however, limited or restricted as toall of its features or as to all combinations or subcombinationsthereof, to the example machine hereof, or to embodiment in oradaptation to machine organizations of either the multiple spindle typeor of the engraving type.

General organization The example machine is of the vertical column andknee type in which a vertical column It extends vertically upwardly froma base H and mounts at the forward side thereof a vertically adjustableknee K. A slide block Illa is mounted at the forward side of column Infor horizontal attests adjustments in either 'difectionon 'a covetahslide lflb (see Fig. 4) "at the upper end-of the'column; Slide blockIlla provides at the'forward side thereof a vertically disposed dovetailslide Hlc which fits into a complementary vertical slide way formed inthe rear side of structure K for adjustment of the knee structure on theslide block upwardly or downwardly relative to column Iii. The knee K isvertically adjustable upwardly or downwardly by means of "a verticalfeed screw Hid carried by slide block Illa and rotated from hand wheelwe carried by the knee. Horizontal adjustment transversely of the knee Kon column I is effected through the medium of a lead screw Inf rotatedby 'a hand crank mg.

The column 18 mounts 'or provides at its upper end a forwardly,horizontally extended cutter spindle unit mounting head structure "[2,which in this example is of greater width than the width of the columnstructure, as will be clear by reference to Fig. 2. At the forward,vertical side of structure [2, a series of vertically disposed spindleunit mounting heads H are adjustably mounted for receiving in verticallydisposed position therein a plurality of motorized cutter spindle unitsS, respectively.

A work table unit T which provides a universally laterally movable worktable mounting component, is mounted in horizontally disposed positiondirectly on the upper side of the vertically adjustable knee K and isadapted to be carried by and moved vertically upwardly or downwardly asa unit with theknee toward or from spindle unit mounting heads H and thespindle units S mounted therein. The table unit T is sliclably mountedon knee K by a dovetail slide M which is received and slldably fittedinto a complementary dovetail groove Ma formed in the under side of thebase of table unit T. Thus, the table unit T may be adjusted on knee Kin directions inwardly toward or outwardly from the column structure l0.Adjustments in or out of table unit T are effected by a usual feed screwMb mounted on knee K, disposed longitudinally of slide I4, in threadedengagement with a usual feed screw nut (not shown) carried by table unitT. Feed screw Mb is rotated in either direction by a hand crank l lc atthe outer end thereof at the forward side of knee K (see Figs. 1 and A.movement transmitting pantograph linkage mechanism P is pivotallymounted and hung from a fixed vertical pivot supported from columnstructure at, with the pantograph mechanism. P disposed horizontally andpositioned at one side of the machine adjacent one end of the table unitT, in this instance the right hand side. Pantograph mechanism P isoperatively coupled directly with the adjacent end of the universallylaterally movable work piece mounting component of table unit T, fortransmitting in sealed relation to such table component, the movementstransmitted to the pantograph mechanism by a tracer style A mounted onand carried by a tracer arm of the pantograph mechanism.

At the forward, right hand side of the machine a master wheel M ismounted in vertically disposed position for rotation about a horizontalaxis on the forward end of an arm structure H, which extendshorizontally forwardly from the right hand side of column structure is(see Figs. 3 and 4); The master wheel M- is adapted to mount on andaround the periphery thereof; a

series of "patterns ra selectiver'positioiiidg by indexing. rotation ofsaid master wheel rd-r traciiig engagement by the 'tracerfstyle 'A. g

A multiple work met mounting and indexing rli'echanism B for indexingsimultaneously work pieces mounted thereon, is mounted on the uni versally laterally movable work table forming component-or table unit "If.This mechanism 33 provides a pluralityof inclexable work holdingfixtures on which" ma "be mouhted the work pieces W (see Figs. 1 and i).The work pieces W are positioned by the work holding fixtures withportions of the upper sides or edges thereof in vertical alignment'withrotary engraving or cutting tools C mounted in the lower ends of thecutterspindle's of the motorized spindle units S. U A pneumatic cylinderand piston unit D (see Figs. '4 and 16) is mounted on and forms acomponent of the work holding and indexing mechanism B, for operation toactuate the work indexing mechanism to index work pieces W mountedthereon into positions to present portions of the peripheral edges ofsuch work pieces for work'- ing engagement with the engraving tools orcut-- ters C.

An air cylinder and piston] unit E is mounted on the left hand sideor'end of head structure 52 (see Fig. 4) for operation to actuate thefeed mechanism for the motorized spindle units S, to effect feed ofthese units simultaneously toward orfrom work table unit T to therebyproject and retract the spindle mounted cutting tools C to and fromworking engagement with work pieces W mounted on the work holding andindexing mechanism B. The operation of the pneumatic cylinder unit D foractuating the'work piece indexing mechanism B, is controlled byas'olenoid operated air control valve unit F located in the air lines tothe unit D -(see Fig. 3'). The actuation of control valveunit F iscontrolled by the e'nergiza tion and de-energizai'tion of the solenoidof the unit which in turn is controlled by suitable interlock switches,to be identified and described hereinafter, in the electrical circuitsto the solenoid. of the valve unit.

The cylinder and piston unit E for actuating the feeding mechanism forthe spindle units S, is controlled by a solenoid actuated air controlvalve unit G located in the air lines to unit E. The actuating solenoidof the air control valve unit G is energized and tie-energized under thecontrol of interlock witches, to be identified and describedhereinafter,- connected into the elec'- trical circuits to the solenoidof valve unit E.

Multiple spindle units and their mounting In the example machine "aseries of four (4) self-contained, motorized spindle unit.- S areprovided for mounting in vertically disposed position in the heads H1The heads H are adjustably mounted on the forward side of structure 52in vertically disposed positions above the work table unit T. n V

Referring now to Figs. 16, 17 and 18, in connection with Figs. lthemotorized spindle units S are identical in design, construction anddimensions and are interchangeable in the heads H. Each spindle unit Scomprises a circular casing 20 within which there is mounted andcontained a motorized spindle assembly 2|, which includes a motor andthe cutter spindle 2 2 driven thereby and rotatively jou'rnaled thereinposition disposed axially of the casing. The-motorized-spindle assembly'2! slidably spindle unit mounting heads H within the casing 20 formounted and contained movement axially in either direction therein. Theposition of the spindle assembly axially of casing 20 is adjustablydetermined by a micrometer adjusting mechanism 23 mounted at the upperend of casing 20 on an end cap 20a.

The arrangement of each motorized spindle unit S is such that themotorized spindle assembly 2| therein is located extending outwardlythrough one end (the lower end) of casing 20, with the cutter spindle 22projecting outwardly beyond the assembly 2|. The outer end of cutterspindle 22 provides the operating end or nose of the spindle and mountsthereon any suitable cutting or engraving tool receiving and securingchuck or holder 22a, in which there may be mounted a cutting tool C.

Each of the cutter spindle unit mounting heads H is formed with an axialbore or passage 30 extending vertically therethrough and having aconstant internal diameter which is substantially the same as theexternal diameter of the casing 20 of spindle unit S, so that, a unit Smay be mounted therein in position extending therethrough with aslidable or running fit. A mounting base 3| is provided extendinglaterally or radially from the rear side of a head H, and this base 3|includes the opposite side vertical flanges 32 by which the head isadjustably mounted on the forward side of structure l2.

The forward side of the head mounting structure I2 is formed with ahorizontal, longitudinally disposed channel |2a therein extendingthereacross. Channel |2a is open at its forward side through thevertical, outer side surface |2b of structure l2. The surface |2b atopposite sides of channel |2a is formed to provide seating surfaces toreceive and against which the base flanges 32 of heads H are adjustablysecured. T-bolt slots |2c are formed in head structure l2 at oppositesides of channel In opening forwardly through seating surface IZb.T-slots |2c are disposed in parallel relation and extend longitudinallyand substantially throughout the width, of the forward end of structurel2.

The spindle mounting heads H are adjustably mounted side by side inpositions spaced along and extending forwardly from head structure l2,with the bores or openings 30 therethrough disposed vertically and inparallelism, by securing the base flanges 32 of each head to the seatingsurfaces I22) by the T-bolts 33 which are received and secured in theT-slots |2c. Thus the are independently adjustable relative to eachother horizontally along head structure H, and radially or laterallyrelative to each other, by loosening the T-bolts 33 of a unit, and thensliding the unit the required distance to the right or to the left toits desired position of adjustment on structure l2.

A motorized spindle unit S is mounted in a head H in vertically disposedposition extending through and slidably received in the vertical bore 30of the head and with the operating nose end 22 of the motorized spindleassembly 2| projected downwardly a distance below the head. A spindleunit S is maintained in mounted position in the head H againstrotational movements relative thereto by a positioning pin 34 which issecured extending through the lower forward or front portion of head Hinto and disposed radially of a spindle unit mounting bore 30. Eachspindle unit S is provided in the for ward side of its case 20 with avertically disposed slot 24 into which the inner projected end of thepositioning pin 34 of the head H is slidably. received. The positioningslot 24 of each spindle unit opens at its lower end through the lowerend of casing 20 to permit of lifting a unit S vertically upwardly toremove the unit from a mounting head.

Vertical bores 35 are formed in each mounting head H opening through theupper side edge thereof and extending a distance downwardly into thehead. These vertical bores 35 are located in diametrically oppositepositions in a head H between the base 3| and the forward side of thehead. A coiled expansion spring 36 is positioned in each of the bores35. Plunger forming rods 31 are mounted in bores 35 and at their upperends are engaged by the end cap 28 of the unit. Rods 31 are formed attheir lower ends to provide the heads 31a of an external diameter to bereceived in and form a free fit with the bores 35 of the heads H forvertical reciprocation thereof in bores 35.

In mounted position of a spindle unit S in the bore 36 of a head H, therods 31 extend downwardly into head bores 35, respectively, with theheads 31a thereof engaged with the upper ends of spring 35 and withthese springs confined under compression between the lower end walls ofbores 35 and the plunger heads 31a, so that, the rods are spring biasedupwardly in engagement with cap 23. By this arrangement there isprovided an anti-backlash means for the spindle unit feeding mechanism,as will be referred to hereinafter.

The casing 28 of each motorized spindle unit S is provided with or hasmachined therein, vertically disposed rack teeth 38 in the rear sidethereof disposed in the vertical plan of the diameter which passesthrough the positioning slot 24 in the forward side of the casing.

Spindle unit feed mechanisms Each head H mounts in a gear trainconsisting meshed gears 40 and 4|. Referring to Fig. 17, the gear 4| islocated in a bore 4|a in base 3|, which bore is horizontally disposedtransversely relative to the base. Bore 4|a opens through one side ofthe base 3|, and a circular block or plug 42 is threaded into the openend of the bore. Plug 42 has an axial bore which slidably and rotatablymounts and receives therein one end of a shaft 43 on which gear 4| isfixed for rotation with the shaft. The opposite end of shaft 43 extendsthrough and is slidably and rotatably received in a bore in the oppositeside of base 3|, and projects outwardly a distance therebeyond toprovide a push button or plunger 43a. A coiled expansion spring 44 ismounted on and around shaft 43 under compression between block 42 andthe adjacent side of gear 4|. Thus, gear 4| is spring biased inwardlyand normally maintained in position in mesh at its forward side with therack teeth 38 of spindle unit S mounted in the head H, and at its rearside with the gear 4|.

By the foregoing arrangement, a motorized spindle unit S may be readilymounted in and removed from a head H by pressing inwardly on the pushbutton end 43a of shaft 43 to thereby displace that shaft and the gear4| outwardly from its position between and in mesh with gear 40 and rackteeth 38 of the spindle unit, to a position out of mesh therewith. Withgear 4| in displaced, disengaged position clear of spindle unit rackteeth 33, a cutter spindle unit S may then be readily inserted in orremoved from a mounting head H.

the flangedbase thereof of a pair of normally Gear til is rotatablyounted on a shaft 45 which is mounted in the inner, flanged portion ofbase 3| of a head H, in horizontal position parallel with shaft 43a. Thegear 40 is rotatably received in a vertically disposed slot or passage40a formed through the inner flanged portion of base 3|. Passage 35aopens at its forward side into bore Ma and at its rear side into thechannel In in the forward side of head mounting structure i2. Gear 55has a diameter such that it projects a distance inwardly into thechannel |2a when the head H in which it is mounted, is attached inmounted position on structure I2, as will be clear by reference to Figs.17 and 18.

A long gear 55 in the form of a toothed shaft or spindle, is mounted inhorizontal position extending longitudinally through channel |2a ofstructure it, and is journaled at its opposite ends in end walls at theopposite ends, respectively, of the channel. This long gear 45 isformed, in this example, with longitudinally disposed teeth forming ribsor splines 46a therearound which extend throughout the length of thegear within the channel |2a. Shaft gear 46 is mounted in position withits axis in the horizontal plane passing through the axes of gears 55and 5|, for meshing engagement by the inner side of a gear 45 in mountedposition of a spindle unit head H on structure I2.

With the multiple spindle heads H in mounted adjusted position on andalong the seating surfaces l2b, each of the gears 40 of a head carriedfeed gear train is thus engaged in driven connection at its inner sidewith the long shaft gear 45, so that, rotation of gear 45 Will effectrotation simultaneously of the head mounted feed gear trains. Withcutter spindle units S mounted in the heads H with the rack teeth 38 ofsuch units in mesh with the inner gears 5| of the feed gear trains,rotation of shaft gear 45 in a clockwise direction will rotate gears 4|of the feed gear trains in a clockwise direction to feed the cutterspindle units S downwardly to operative, working positions, whilerotation of shaft gear 46 in a counterclockwise direction will effectfeed of the spindle units .3 upwardly to raised, non-working positions.

The arrangement of the spindle unit carried rods 35 and head mountedsprings 35, is such as to function to eliminate backlash in the feedgear trains and shaft gear 56, and thus insure precise synchronizationof the feeding movements imparted simultaneously to the spindle units Sby rotation of the shaft gear 45. With the shaft gear 45 toothedthroughout the length thereof within channel |2a by the unbroken,parallel teeth Mia, any mounting head H may be individually adjusted ineither direction horizontally along the mounting seats I21) of structurel2, with the inner gear 55 of the feed gear train merely sliding alongshaft gear 45 in continuous mesh therewith. Such an adjustment of a headmay be effected independently of the other heads H, and withoutdisconnecting the driving connection between the gear 40 of the adjustedhead and the shaft gear 46, so that in any adjusted position laterallyof a head H the feed gear train thereof will be automatically maintainedin driving connection with shaft gear 46.

In the machine of the example, four (4) mounting heads H are shown, butthe width of head mounting structure may be considered to be such as topresent seating surfaces |2b of a length to accommodate and mount six(6) of the heads H. Obviously anylessernumber of the heads H may beemployed if desired, and spindle unit mounting heads of smaller widthdimensions than those of heads H of this example, may be utilized, sothat, a greater number of heads may be mounted on the seating surfaces222 of structure l2. Conversely heads of greater dimensions may beemployed, so that the maximum mounting capacity of structure |2 will bereduced. Or a greater width may be provided for mounting structure It toform head seating surfaces of greater length to accommodate a greaternumber of heads H.

Spindle unit feed actuating means The shaft gear :35 which drives thefeed gear trains lu-4| of each spindle unit mounting head H, is rotatedin either direction by the pneumatic cylinder and piston E. Referring toFig. 16, this unit E is mounted at the left hand side of head mountingstructure l2, being suitably enclosed or encased, and comprises an aircylinder 50 dis posed in a forwardly, upwardly inclined position andmounting therein a piston 5| with a piston rod 52 extending outwardlytherefrom through the forward head 55 of the cylinder.

The outer, forward end of the piston rod 52 is pivotally coupled by alink 52a to the upper end of a crank arm 53 which is attached to andextends upwardly from the outwardly extended, adjacent exterior end ofthe shaft gear 46. The coupling linkage of piston 52 to shaft gear crank53 is such, that with piston '52 at the end of its rearward, downwardstroke, shaft gear 45 is rotated counter-clockwise to position withspindle units S in heads H fed upwardly to raised, nonworking positions,while with piston 5| at its limit of forward, upward movement, shaftgear 45 is rotated in a clockwise direction to feed the cutter spindleunits downwardly to operative, working positions.

The inner, lower end of cylinder 50 is closed by a head 54. Head 54 isprovided with an air intake-exhaust passage 51 therethrough, opening atits inner end into cylinder 5| and at its outer end opening through theperipheral side wall of head 54 where it is connected with an airsupplyexhaust line 58.

A collar 59 is secured on rod 52 adjacent the forward upper end thereof.This collar '59 provides at the inner side thereof an annular abutmentsurface 59a therearound which is precisely machined or formed to fit andengage against a complementary abutment surface 551) formed at the outerside of the upper end cylinder head 56. Surface 56b thus forms anaccurate and precisely located abutment stop for engagement by surface59a of collar 59 to limit the inward stroke of pis ton 5| to therebydetermine accurately the maximum raised positions of spindle units S. v

A coiled expansion spring 55 is mounted on and around piston rod 52between piston 5| and the inner side of the outer end cylinder head '56.Spring 55 acts to continuously bias piston 5| and rod 52 rearwardly anddownwardly in cylinder 50 to its limit position with abutment surface55a of collar 59 engaged against stop surface 56b of head 55.

Forward, upward movement of piston 5| is effected by admitting air underpressure into the lower end of cylinder 50 through passage '51, todevelop pressures acting on piston 5| of a magnitude to overcome thebiasing forces of spring 55 to thereby force piston 5 and rod52 upwardlyto effect feed downwardly of the spindle units S to operative, workingpositions. The inner side of cylinder head 56 provides an accuratelyformed abutment surface 56a. for engagement by a complementary surfacevBib. formed on and around the adjacent side of piston 5|, an abutmentstop for accurately limiting forward movement of the piston and downwardfeed thereby of the spindle units S in the head H. These abutment orstop surfaces 511) and 56a are accurately located and positioned to givethe cutter spindle units S a precise, predetermined maximum lowered ordepth position.

It is to be noted that in Fig. 16 the cylinder and piston unit E isshown in air pressure actuated position with the cutter spindle units Sfed downwardly and being maintained by air pressure in cylinder 58 inlowered, working positions for engaging cutter tools in the spindles 22,with work pieces W on the work holding and indexing mechanism B. When itis desired to feed the spindle units S upwardly to raised positions, theair supply through supply line 58 is cut oh and the line is then openedto atmosphere for. release of pressure in and exhaust of air fromcylinder 50, under the action of biasing spring 55, which then acts toforce piston rearwardly to rotate shaft gear 46 in a direction to raisethe cutter spindle units S through the operation of the feed mechanism.

Each of the cutter spindle units S is a selfcontained, motor driven unitand each in mounted operative position in its head H is supplied withelectrical current by a flexible conductor cable L. These individualcircuit cables L to the spindle units S, are each detachable fromelectrical connection with the motor of its unit and from the unit, whenit is desired to remove a unit from a mounting head H. The cables Lextend to a switch panel LS which mounts a series of four (4) switches,SI, S2, S3 and S4, for selectively opening and closing the supplycircuits through the cables L to the units S, respectively. Thus, themotorized spindle units S may be individually, selectively operated orcut off by the operator from the switches on the switch panel LS. Inthis instance this panel, with the switch actuating levers of theswitches, is mounted on the right hand side of the head mountingstructure [2, with. the switch operating levers in position accessibleat the exterior thereof, as will be clear by reference to Fig. 3. Theswitches of switch panel LS are connected with a suitable source ofelectrical current (not shown) in the usual manner for supplying currentthrough cables L to the motors of the spindle units S.

The sensitive work table unit The work table unit T which is mounteddirectly on and is vertically adjustable as a unit with the knee K, isof the sensitive or socalled duplicator table type and provides at itsupper side the movable work piece supporting and translating tablecomponent 80 mounted for universal lateral movements in a horizontalplane. Referring now to Figs. 11 through 15, in connection with Figs. 1and 4, the table unit T includes a base plate 61 which is directlymounted on knee K for adjustment thereon in the transverse or in and outdirection relative to the machine, bythe dovetail slide M on knee K,which is slidably received in the dovetail groove [4a at the under sideof base plate 6!.

The base plate 6| is provided along and adjacent each opposite,transverse side edge. thereof with a series of upstanding lugs, which inthis to thus providev aeeaese instance include a forward lug 62, anintermediate lug 63, and a rear lug 64, as will be clear by reference toFig..11. The lugs 62, 63 and 64 of each series, are spaced and alignedtransversely of base 6! and are provided with transversely disposed,axially aligned horizontal bores therethrough. A rod member 65 issecured extending through the bores of the aligned lugs at the left handend of base 6| with the opposite ends of the rod secured in the forwardand rear lugs 82 and 64,, respectively, and with the intermediateportion of the rod extending through and intermediately supported by thelug 63. An identical rod member 66 is similarly mounted and securedinthe series of base lugs 62, 63 and G5 at the right hand end of thebase plate 6!. Thus there is provided at opposite ends of base 6| therods 65 and 65 which are disposed horizontally in parallelism with theiraxes in the same horizontal plane and extending transversely of baseplate 6! to. define straight line paths.

A carriage or cradle ll! of generally rectangular plan form is providedhaving longitudinal and transverse dimensions such that the cradle maybe supported in position between rods 65 and 66 for limited movements ineither direction transversely thereon above base plate 6| in directionsin or out relative to' the machine. At its opposite ends cradle 10includes the upstanding flanges H forming vertical end walls from theouter side of which extend the spaced arms 12 providing at their forwardlower ends the antifriction bearing mounting bolsters 13. Each pair ofbearing bolsters I3 is formed with axially aligned, horizontallydisposed bores therethrough.

The bearing bolsters 13 at the left hand end of cradle Til mount thereinthe linear, annular form antifriction bearing assemblies 653 which aremounted on. and slidably receive therethrough the rods 65 at the. lefthand end of base plate 61 with the forward bearing bolster I3 and itscontained linear bearing positioned intermediate rod supporting lugs 62and 13 and with the rear bearing bolster 13 and its contained linearhearing mounted on the rod 65 between the intermediate rod supportinglug 63 and the rear lug B4. The spaced bearing bolsters '53 at the righthand end, of cradle 10 mount therein the linear, annular formantifriction bearing assemblies 663 which are mounted on and slidablyreceive therethrough the rod. 66 at the left hand end of base plate El,with the forward bearing bolster l3 and its linear bearing positionedbetween the forward and intermediate rod supporting lugs 62 and 63, and.with the rear bolster 13 and its linear bearing mounted on the rod 65between the intermediate and rear rod supporting lugs 63. and 54.

By the foregoing mounting and arrangement, the cradle 10 is mounted. andsupported at its opposite ends in a horizontal position from the spacedparallel rods. 65 and. 66, constrained or limited to straight. linemovements on the rods transversely across base MI, in directions in" andout. relative to the. machine. The linear bearing assemblies. 653 andBBBv provide minimum friction. slidable mountings. for the cradle 10 onrods 65 and 66, so that, the cradle is highly sensitive and responsiveto. movement by the application thereto of forces of relatively smallmagnitudes.v

Adjacent the rear, longitudinal side of cradle 10 there is mounted,extending. between the opposite, upstanding. flanges H... a rod. member14. Rod 14 is secured at its opposite ends in aligned bores 14a inopposite end flanges 1| with the rod in horizontal position with itsaxis perpendicular to the axes of the parallel, transversely disposedrods 64 and 66. The rod end receiving bores 1 3a are located at the rearsides of and opposite bearing bolster supporting arms 12, respectively,and these bores may be extended outwardly through arms 12 for readyassembly and removal of rod 1 1 to and from mounted position. Suitableset screws 1401 may be employed for securing the rod ends in flanges H.

A rod member 15 identical with rod 14, is mounted in position along andadjacent the forward longitudinal side of cradle 16 in horizontalposition parallel with the rearwardly mounted rod 14. Rod 15 is securedin mounted position with its opposite ends received in bores 15a offlanges 1! by set screws 15:2. The bores 15a may be extended outwardlythrough the adjacent arm 12, respectively, to permit of ready assemblyand removal of the rod. The cradle 16 may be provided with upstandinglugs 16 intermediate the opposite end flanges 1| for receivingtherethrough and providing intermediate support to the forward and rearrods 14 and 15, respectively.

The work piece mounting and translating table component of member 80 ofthe table unit T, is slidably mounted on the parallel rods 14 and 15 andis constrained by these rods to straight line movements in oppositedirections in directions longitudinally of the machine and perpendicularto the path of in and out, transverse movements of cradle on the rods 65and 66.

The table 80 is provided with spaced lugs 8! depending therefromadjacent the rear longitudinal side thereof with each of these lugsmounting therein a linear, annular type antifriction bearing assembly14B. These bearing assemblies are mounted on and slidably receivetherethrough the rod 14 with lug 8i and its bearing 14B located betweenthe left end flange II and intermediate supporting lug 16, and the otherlug 8i and its bearing 14B positioned on rod 14 between the right handend flange 1| and the intermediate rod supporting lug 16.

A pair of depending, spaced lugs 82, identical with lugs 8|, areprovided at the under side of table 80 adjacent the forward longitudinalside thereof. Each of these lugs 82 mounts therein a linear, annulartype anti-friction hearing assembly 153, with these bearing assembliesmounted on and slidably receiving therethrough the forwardly located rodof cradle 10. One lug 82 with its linear bearing 15B is positioned onrod 15 intermediate the left hand end flange 1| of the cradle 10 and theintermediate supporting lug 16, while the other lug 82 and its linearbearing 15B are located on rod 15 intermediate the right hand end offlange H and the intermediate supporting lug 16.

Each of the bearing assemblies 65B, 65B, 14B and 15B is identical and inthis example, is comprised by a known commercial type of linear, annularor sleeve form of antifriction bearing assembly. The construction of theexample bearing assembly is illustrated in Fig. 13, and comprises asleeve 11 within which there is con centrically mounted and confined atubular retainer 18 which receives and through which a rod or shaft ismounted. The retainer 18 is provided with and mounts a plurality ofoblong circuits of antifriction balls 19. Each of the ball circuits 19presents two (2) straight sides,

with one straight side 1911 in bearing contact between an inner surfaceof the ball bushing 14 sleeve and the rod or spindle extending throughthe assembly. The antlfriction balls in the remainder of each circuitare free to roll unloaded, in clearance provided in the sleeve.

The horizontally positioned work piece mounting table component ormember 86 of table unit T is thus movable transversely with the cradle10 as a unit, in and out relative to the machine on and with the table86 and cradle 16, constrained to straight line paths by the spaced,parallel rods 65 and 66. Table 86 is also movable on and independentlyof cradle 10 in either direction longitudinally of the machine, on andconstrained to straight line paths by the spaced, parallel rods 14 and15 which are positioned with their axes perpendicular to the straightline paths of transverse movements of the table and cradle 10 on rods 65and 66. And, by simultaneous compound movements of the table 80 and ofthe cradle 10 along the pairs of rods 6566 and 14-15, respectively, thetable is thereby universally laterally movable on base 6! in one plane,in this instance, a horizontal plane.

The table 80 is provided with the usual T- slots 80a in the upper sidethereof extending longitudinally across the table for the purpose ofmounting on the table, work pieces or work piece holding fixtures.

Due to the mounting of the cradle 10 and the table 80 by means of thelinear, antifriction bearing assemblies 65B, 66B, 14B and 15B slidablymounted on the respective supporting track forming rods 6566 and 14-15,the table 80 is rendered extremely sensitive and highly responsive totable moving forces and to the directions of such forces, applied to thetable. The construction and mounting of the base 6|, cradle 10 and thetable 80, together with the mounting arrangement of the base carriedrods 65 and 66 and the cradle carried rods 14 and 15, together with theuse of commercially available types of linear, antifriction bearingassemblies, make it possible to construct and to assemble such tableunits at relatively low manufacturing costs by eliminating the necessityfor manufacturing specially designed and constructed antifrictionbearing slide arrangements for the table unit components, while at thesame time providing a construction and assembly which is precise andhighly sensitive under production conditions of operation and use, withlong wear and with maintenance reduced to a minimum.

The table unit itself, together with the combination thereof with thesupporting or knee structure K, by which the table unit T is directlymounted on the knee, provides compactness in the direction transverselyof the unit, in this instance in the vertical dimension, so that amachine with which the unit and its supporting structure are used, hasan increased capacity for mounting a wider range of sizes of workpieces.

A table unit T of the invention is in no sense limited or restricted toadaptation and use with the machine of this example, or to thecombinations in which it is found in this example machine. Table unitsof the invention are intended for and are adapted in the form hereshown, or in various modifications thereof, to general use as auniversally, laterally, movable sensitive type of work table.

No claim to the sensitive work table unit per 'se,

except as a'component in the combinations in claims hereof, is madeherein, as such sensitive work table unit and the construction andcomfined on slide bar 92 in blnations of elements thereof, is disclosedand claimed in my copendingfU- S. patent application SerialNo. 359,581,filed as. a division of this application.

The pantograph and sensitive table combination The pantograph mechanismP is of the parallelogram linkage type, and is suspended from a fixedpivot supported from the machine frame structure at the righthand sideof the machine, with the pantograph positioned in a horizontal planeparallel with the plane of the universally laterally movable, sensitivework table 80. The pantograph mechanism P so positioned is operativelycoupled with the right hand end of table T for translating andtransmitting to the table 89 in sealed reduction, the movements of thepantograph controlling. tracer A as this tracer scans the pattern on themaster unit M.

Referring to Figs. through. 10, in connection with Figs. 1 2 and 3, thepantograph mechanism P comprises the spaced, parallel, inner slide bar99 and outer bar 9i, and the spaced, parallel forward and rear links 92and 93, pivotally coupling and connecting bars 90 and 9! to form theparallelogram linkage in the usual manner. The forward link 92constitutes a slide bar, while the outer bar 9| is forwardly extended toconstitute a tracer arm 94 which mounts at its forward end the tracerunit A.

The pantograph P is pivotally supported and hung from a verticallydisposed pivot pin or stud 95 which is carried in and depends from theouter end of a forwardly and outwardly extended hanger arm 96 of abracket structure 91 which is supported on the horizontally disposedupper side surface of the mounting base l9, by which the master wheelmounting arm 15 is attached to the right hand side of the framestructure of the machine. Base I6 is provided with a T- slot "5a in theupper horizontal surface thereof which is disposed transversely of themachine. Pantograph mounting bracket structure 91 is adjustably securedin position on base l6 by a T-bolt 91a attached in slot id, to permit ofadjustment of the bracket structure with the pantograph P hungtherefrom, in either direction transversely relative to the machine.

The vertical pivot stud 95- is journaled in an anti-friction bearingassembly 95a (see Fig. 7) in the bracket arm 96, and this stud mounts atits lower end the slide block 98 within which the slide bar 96 of thepantograph is adjustably secured. Thus, the pantograph mechanism P as aunit, may be adjusted relative to pivot stud 95 to thus adjust theposition of the axis of that stud longitudinally of bar 99.

The forward link of slide bar 92 is positioned below bars 90 and 9!, andthe forward end of bar 99 mounts a fixed pivot pin 90a which dependstherefrom and which is journaled in an antifriction bearing assembly992) mounted in bar 92, for relative pivoting or rotation of bars 99 and92, as will be clear by reference to Fig. 7. A slide block 99 isslidably mounted and conposition at the underside of that bar and beingslidable longitudinally in either direction therealong. I

The rear link 93 of the pantograph mechanism P is positioned below endof link 93 is pivotally coupled to the rear end of link 99 by a pivotpin 99c fixed in and depending from bar 99 and journaled in anantiiriction bearing; assembly 9311 mounted in link 93,

bars 90 and 9!. The inner.

=aswill be clear; by reference to. Fig. 8. The outer end of'link 90ispivotally coupled to the rear end of outer bar 9| by a pivot pin91afixed. in and depending frombar9l andv journaled in an antifrictionbearing assembly 93b mounted in the outer end of link 93, as shown inFig. 9. The outer end of forward link or slide 92 is pivotally coupledto bar 91 by a pivot stud 9lb fixed in and depending from bar 9| andjournaled in an antifriction bearing assembly 92a mounted in the outerend of link or slide bar 92, as shown in Fig. 10.

The pantograph mechanism P is thus adjustable in the usual manner tovary the ratio of scaled reduction of the movements transmitted to themechanism by the tracer arm 94, by adjusting the bars 90 and 92 in theslide blocks 98 and 99, respectively, to relatively position the axes ofpivot pins 95 and 9011 along and relative to the longitudinal axes ofbars 99 and 92, respectively. In the example hereof, movement in scaledreduction of the movements of the tractor T at the outer end of tracerarm 94, are taken off from the pantograph mechanism at the slide block99 which adjustably, slidably receives pantograph bar 92.

The slide block 99 is coupled with the universally laterally movablesensitive table 89 by means of a coupling mechanism which permits ofvertical adjustment upwardly and downwardly of table with table unit Tand knee K as the unit, without displacing or moving pantographmechanism P from the horizontal plane in which it is hung and supportedby the hanger bracket 96. In the particular adaptation of such acoupling mechanism for the example machine, referring now to Fig. 7 inparticular, in connection with Figs. 2 and 5, the slide block 99 mountstherein an annular antifriction bearing assembly 99a of the doublebearing type, with the axis of the assembly vertically disposed. Asleeve member 99b is mounted and journaled in its upper end in bearingassembly 99a and depends vertically downwardly therefrom a distancebelow slider block 99. A headed stud 990 is mounted and received insleeve member 9912 and extends downwardly therethrough to provide anexternally threaded lower end on which there is mounted a fastening nut99d to engage and secure the stud and sleeve together as a unit assemblyjournaled in bearing 99a.

An outwardly extended, horizontally disposed rod member 83 is clamped atits rear end on the sleeve in stud assembly 99b-99c, with its axisparallel with the transverse axis of the machine. The forward end lengthrod member 93 is formed of a reduced external diameter. A link member 84is pivotally mounted on the reduced diameter portion of rod member 83,and a coiled expansion spring 85 is mounted on member 83 between theshoulder 83a formed at the inner end of the reduced diameter portion andthe inner side of link 84.

The outer end of the reduced diameter portion of rod 83 is provided withexternal screw threading 83b thereon (see Fig. 5), and a micrometerbarrel 83 is threaded onto rod 99 and provides a reduced diameter scalebearing hub portion 86a at the inner side thereof for engagement by theadjacent forward side of link 84. A micrometer scale 86s is provided onand around hub portion 8911 with an index line 86b being provided on theupper side of link 34 for selective alignment by rotation of barrel 86with the micrometer divisions of scale 98s. A lock nut 890 is alsothreaded on red 83 at the outer side of micrometer barrel 86, forreleasably looking barrel 86 in an adjusted position. The spring 85continuously biases link 84 outwardly on rod 83 into adjusted positionengaged against microrneter barrel hub 86a. The position of link 84axially on rod 83 is thus adjustable by adjusting the position of themicrometer barrel 86 inwardly or outwardly on the rod 83.

The inner end of link member 84 is provided with a forwardly extendedcrank pin or shaft member 87 which is disposed radially relative theretoand which extends forwardly and horizontally therefrom. Shaft 8? isaccurately formed and positioned so that its axis is in substantiallyprecise parallelism with the axis of rod member 83 on which the outerend of link member 84 is rotatably mounted.

The right hand end wall of table as has the horizontally disposed T-slot80b therein opening outwardly therethrough, and a bearing block member83 is adjustably secured in the T-slot 80b in position attached to table80 for movement therewith as a unit. This bearing block 88 provides ahorizontally disposed bearing 88a therein which receives and in whichshaft 81 of the coupling link member 84 is journaled for pivoting. Thustable 8-9 is coupled with the slide block 99 of pantograph mechanism Pand is universally laterally movable by universal lateral movements ofthe slide block by the panto'graph mechanism under the control of thetracer T at the forward end of pantograph tracer arm 94. The position ofcoupling link member 84 relative to slide block 99 and pantographmechanism P, along the axis of rod member 83 is adjustable by themicrometer adjusting mechanism which includes the micrometer barrel 86.

By the foregoing coupling arrangement, the table 88 may be verticallyadjusted upwardly or downwardly without interfering with or changing theposition or level at which pantograph mechanism P is hung and supported.On upward or downward adjustment of table 88, the coupling link 84merely pivots or swings about the horizontal, parallel axes provided byrod member 33 and the shaft or pin 81 which is journaled in the bearingblock 88 carried by table 89.

The table unit Tis also capable of adjustment transversely and/orlongitudinally with the knee as a unit on the knee slide I4 and on thecolumn slide ifib, while the pantograph mechanism P is adjustabletransversely of the machine by a"- justing the supporting bracket 9% onbase member 55.

The combination of the universally laterally movable table with itsminimum friction mounting comprised of the rods and linear antifrictionball type bearing assemblies, together with the pantograph mechanism Pwith its antifriction bearing pivots, substantially eliminates alllooseness and play to thus insure precision reproduction with minimuminertia and highly sensitive responses as precise movements in sealedreduction by the table 30, to movements of the pantograph mountedtracer'on the pantographcontrolling tracer arm 94.

Tracer and indemable master units Referring to Fig. 19, the tracer unitA embodies a tracer stem I Elli which is slidably mounted in avertically disposed tubular hub or sleeve member I GI formed, in thisinstance, integral with tracer arm as at the outer end thereof. Tracerstem Ilia has a plunger head I02 at the upper end thereof forming anoperating'button thereupper end of stem I09 under compression between ashoulder provided by housing I DI and the under side of button I02, sothat, the tracer stem is normally biased to raised position out oftracing or scanning engagement with a pattern on the master wheel Mtherebelow. At its lower end tracer stem Hid removably mounts a stylusI8 3 depending therefrom for tracing engagement with a pattern on masterwheel M, when the tracer stem is depressed. Tracer stem I90 also mountsat its lower end a cap member providing an upwardly extending annularflange I therearound which slidably extends up over and around theexterior of housing IOI and provides a camming surface for a purpose tobe hereinafter described. I

The indexable master unit is constituted by a master wheel M having alaterally forwardly projected annular flange III] therearound providinga peripheral surface III for receiving and removably mounting thereon aseries of patterns IIZ (see Fig. 1). These patterns i I2, in the presentexample, are individually removable and replaceable on the surface III,which surface may be suitably formed to provide seats or bases spacedtherearound for mounting the patterns. The master wheel M, referring nowto Fig. 19 in connection with Fig. 5, is rotatably mounted in verticallydisposed position at the forward side of arm structure I5 for rotationabout a horizontal axis disposed transversely of the machine, inposition with the highest portion of the upper side of rim IIO locateddirectly below the tracer unit A at the outer end of tracer arm 94. Therotatable mounting for pattern wheel M embodies, a spindle II ljournaled in antifriction bearing assemblies Ilsa carried in a hubportion l5a at the forward end of arm structure I5. 'The hub portionIIiiA of master wheel M is secured to the forward end of spindle H4 by asuitable securing bolt or the like member Illlb. A circular shield ismounted on the hub I5a and provides a forwardly extended flange Iliaspaced outwardly from and around and concentric with the patternmounting flange III) of wheel M, with this flange IISa cut away at theupper side thereof to form a tracing station at which a selected patternH2 is positioned and exposed for tracing engagement by tracing style Hil of the tracing unit A. In the instant example, pattern wheel M ismanually rotatable in either direction to position a selected pattern H2at the tracing station at the upper high side of the wheelM.

An indexing mechanism is provided for re' leasably locking master wheelM in position with a selected pattern at the tracing station. The masterwheel M at the rear side thereof is provided with a spaced series ofindexing notches N therearound extending radially inwardly from theperiphery of the wheel (see Figs. 2, 5 and 19), with each of the notchesN lying in a radial plane which passes through the center of a patternmounting base on the surface II I of wheel M. A supporting housingstructure II 6 is se cured at the upper side of hub I5a of arm structureI5 on the rear of shield I I5 and this housing structure mounts ahorizontally disposed casing I I! within which there is slidably mountedan indexing plunger H8. Plunger II8 projects forwardly from casing H Iin position for engaging and seating at its forward end into an indexingnotch N of wheel M. Indexing plunger 8 is spring biased by a spring I IBa to forwardly projected. indexnotch engaging position.

A coil spring m3 is mounted around the r

